The present invention relates generally to chemical sampling sinks, and more specifically to chemical sampling sinks for use in the silicon processing industry.
Chemical sampling sinks are used in a variety of industrial applications to take samples of chemicals in a controlled environment, free of pollutants. In the semiconductor processing industry, chemical sampling sinks are used to take samples of high purity chemicals, such as ammonium hydroxide, as a quality control measure. The samples are analyzed to ensure that the purity of the chemical is within a desired range.
To prevent contaminants from entering the sample, current chemical sampling sinks include an enclosure surrounding a liquid chemical dispenser. The enclosure includes a door through which a receptacle may pass to be positioned below the dispenser. Once the receptacle is inserted, the door may be shut and chemical poured from the dispenser.
Current chemical sampling sinks include a drain to carry away spilled or overflowing liquids, and an exhaust to draw air out of the enclosure. One problem with current chemical sampling sinks is that the exhaust systems tend to draw contaminated air into the enclosure. In silicon processing environments, fine silicon dust, present in minute amounts in the air, may find its way into the enclosure through gaps in the enclosure walls or door, thereby contaminating the sample. Other contaminants, such as dirt and pollen, may also be drawn into the enclosure through the gaps. Because chemical sampling sinks are used to take samples of extremely high purity chemicals, even minute amounts of contaminants can ruin a sample.
Another problem with current chemical sampling sinks is that operators of the sinks are able to dispense chemical liquids into receptacles while the door of the enclosure is open. This may expose the sample to airborne contamination entering through the door into the enclosure. In addition, dangerous chemical droplets or gases may be released from the sampling sink through the open door into the environment and/or onto the operator. Because many of the chemicals sampled with chemical sampling sinks are potentially harmful, uncontrolled release of these chemicals is a potential environmental and health risk.
In addition, current chemical sampling sinks are translucent and allow ultraviolet (UV) radiation to enter the interior of the sink and damage components, or the sinks are made of material that deteriorates when exposed to UV radiation. Finally, current chemical sampling sinks use push-button valves, and require operators to continuously press the buttons for lengthy periods of time in order to dispense a sample.
It would be desirable to provide a chemical sampling sink that does not draw airborne contaminants into the enclosure, prevents dispensing of chemicals with the door open, is UV-resistant, and/or does not require an operator to press a button continuously for lengthy periods to dispense a chemical.
A chemical sampling sink and method are provided. The chemical sampling sink typically includes an enclosure configured to contain a receptacle, and a chemical supply line extending into the enclosure, the chemical supply line including a dispenser configured to deliver a liquid chemical to the receptacle. The chemical sampling sink also includes an exhaust line attached to the enclosure, the exhaust line being configured to suction gases from the enclosure, and a filter positioned on the enclosure, the filter being configured to remove contaminants from air drawn into the enclosure as gases are suctioned from the enclosure out the exhaust line. The sink may also have valves that do not require operators to continuously press a button to dispense chemicals, and the sinks may be made of a material that is UV resistant. Sinks that have new valves or that are UV resistant may or may not include a filter to remove contaminants from air drawn into the enclosure and sinks that include such a filter may or may not have new valves or UV resistant material.
The method typically includes providing an enclosure, placing a receptacle within the enclosure, the receptacle being configured to hold a chemical, dispensing a chemical through a dispenser into the receptacle within the enclosure, suctioning gases from the enclosure to an exhaust line, and filtering air drawn into the enclosure during suctioning.